Student's T Probability Distribution
Student's T Distribution
Student's T Distribution is very similar to a Standard Normal (Z) Distribution. The graph of a T PDF is a bell-shaped curve symmetric about the mean of 0. It always has a standard deviation just slightly above 1.
Start by deselecting everything except for PDF. This will show the graph of the PDF. There is a different T distribution for every choice of a parameter called the Degrees of Freedom (df). Adjust the slider/input box to manipulate df.
Now check the box for Standard Normal. This Z curve is graphed in black. Notice that these two PDF graphs are extremely similar, and the larger n is the more the two graphs are the same.
Deselect Standard Normal and select Probability for different probabilities are computed and illustrated as vertical lengths on the CDF curve if CDF is checked, and they are represented as areas between the PDF curve and the x-axis if PDF is checked.
Similarly checking Inverse Probability allow the user to enter a probability and see it illustrated on the PDF and/or CDF curves.